Hydraulic fluid compositions



United States Patent 3,379,644 HYDRAULIC FLUID COMPOSITIONS WilliamKatzenstein, Broomal, Pa., assignor to General Aniline & FilmCorporation, New York, N.Y., a corporation of Delaware No Drawing. FiledMar. 16, 1966, Ser. No. 534,663 5 Claims. (Cl. 252-73) The presentinvention relates generally to hydraulic fluids useful fortransmittingpressure in closed systems. More particularly, it relates to a new anduseful hydraulic fluid composition containing an ethoxylated long chainalkylated phenol thickening agent.

Considerable work has been done on the problem of developing a suitablepressure transmitting fluid for use in servo-mechanisms and hydraulicbraking systems and the like. Hydraulic fluids having a castor oil baseor a polymer-thickened petroleum base have been employed but have notbeen entirely satisfactory due to the fact that they constitute aserious fire hazard. Because of the inflammability of these conventionalhydraulic fluid compositions, there is a'constant danger of firesresulting from breaks in high pressure hydraulic fluid lines or fromleaks rising from mechanical or packing failures or from other obviousmeans. Moreover, these conventional hydraulic fluid compositions areundesirable because they tend to swell the various parts made of rubberor the like, which are used in pressure transmitting systems. Variousglycolbase hydraulic fluids have heretofore been proposed, but haveproven unsatisfactory due to their low viscosity and, more particularly,due to their excessive cost. Various water-base hydraulic fluids havealso been proposed, but have proven unsatisfactory due to their lowsurface tension which results in a marked tendency of the fluid to leakout through materials which would normally confine a fluid of highsurface tension.

Accordingly, one object of the present invention is to provide a new anduseful hydraulic fluid composition which will overcome the disadvantagesof the prior art compositions.

Another object of the present invention is to provide a new andimproved, low-cost hydraulic fluid composition intended for useparticularly in hydraulic braking systems or servo-mechanisms or thelike which is non-flammable, of good viscosity and which will notappreciably corrode, attack or otherwise deliteriously affect thevarious metallic and non-metallic materials commonly employed in servosystems or hydraulic braking systems or the like. Other objects andadvantages of the present invention will be readily apparent from thefollowing detailed description as well as the appended claims.

Generally speaking, the present invention contemplates a new andimproved hydraulic fluid composition prepared by the addition of aneifective, low cost, compatible thickener to an ethylene glycol-waterfluid composition. Said new and improved composition may also containsmall amounts of appropriate and well known additives, such as corrosioninhibitors, vapor-phase inhibitors and also soluble detergents ifdesired.

More particularly, the instant invention pertains to hydraulic fluidcompositions containing ethylene glycol, water, and as the thickeningagent an ethoxylated dinonyl phenol and if desired, a small amount ofthe above mentioned additives. The ethoxylated dinonyl phenol referredto in this invention is one in which dinonyl phenol has been condensedwith about 12 to 18.5 molar proportions of ethylene oxide, in otherwords, one in which the polyoxyethylene radical comprises 60-70% byweight of the compound. It may also be defined as ethoxylated dinonylphenol +60-70% EtO. While it is obvious that the amount of thickener tobe used depends on the viscosity 3,379,644 Patented Apr. 23, 1968 "iceof the fluid that the particular pump and hydraulic system requires, itis preferred to use this thickener in amounts comprising approximatelyfrom 8-25% of the total formulation of the hydraulic fluid composition.Due to the use of this low cost thickener, the economics of glycol-waterhydraulic fluids are appreciably more attractive and the viscosity ofsaid fluids has been improved. The ethylene glycol-water mixture of thisinvention may consist essentially of from about 40-65 parts by weight ofethylene glycol and 35-60 parts by Weight of water. However, it ispreferred to utilize a glycol-water weight ratio in the range of 50-65parts of ethylene glycol and 35-50 parts of water. Thus the instantinvention is directed to a hydraulic fluid composition comprising (1) to92 parts by weight of an ethylene glycol-water mixture and (2) as athickening agent, 25 to 8 parts by weiyht of an ethoxylated dinonylphenol in which its polyoxyethylene radical comprises 60 to 70% byweight of said ethoxylated dinonyl phenol; parts of said ethyleneglycol-water mixture consisting essentially of about 40 to 65 parts byweight of ethylene glycol and about 60-35 parts by weight of water. Asexamples of the above mentioned additives that may also be present, ifdesired, in a small amount such as from about 0.1 to 5.0 parts by weightof the total hydraulic fluid composition, there may be mentionedinhibitors such as sodium mercaptobenzothiazole, orthobenzoicethanolamine, polymethylsiloxane, 2-amino-2-methyl-l-propanol anddiisopropylamine nitrite.

The unique" discovery that the instant ethoxylated dinonyl phenols maybe used as viscosity improvers for glycol-water hydraulic fluids is mostsurprising since other ethoxylated higher alkyl phenols have been foundto be unsatisfactory in that they do not appreciably affect theviscosity and/ or precipitate out at lower temperatures. The ethoxylateddinonyl phenols used in this invention may be prepared by theconventional known process of reacting the dialkylphenol with thealkylene oxide, for example, as shown in US. Patent 2,593,112, issuedApr. 15, 1952.

The following examples are illustrative of the present invention and arenot to be regarded as limitative. It is to be understood that all parts,percentages and proportions referred to herein and in the appendedclaims are by weight unless otherwise indicated.

Example I A novel hydraulic fluid composition was prepared by adding 8parts by weight of dinonyl phenol condensed with about 15 molarproportions of ethylene oxide, i.e., one in which the polyoxyethyleneradical comprises 65.8% by weight of the compound (hereinafter definedas ethoxylated dinonyl phenol +65.8% EtO), to 92 parts by Weight of a50:50 percent mixture of ethylene glycol and water. The resultingcomposition is an excellent hydraulic fluid which is nonflammable. Asecond composition was prepared by following the same procedure exceptthat 12 parts by weight of the ethoxylated dinonyl phenol +65.8% EtOwere used. The viscosities in centistokes at 100 F. and F. of the aboveprepared compositions were determined and compared to a mixture of 50parts of ethylene glycol and 50 parts of water free from saidethoxylated dinonyl phenol +65.8% EtO. The results were as follows.

TAB LE 1 Ethylene Glycol-Water Cone. of Ethoxylated KV-130 50-50 partsby wt.

Dinouyl Phenol plus 65.8% EtO 3 Example II By way of comparison theprocedure in Example I was repeated to prepare two separatecompositions, one of which contained 8 parts by weight of nonyl phenolcondensed with about 10.5 molar proportions of ethylene oxide(ethoxylated nonyl phenol +67.8% EtO) and the other contained 8 parts byweight of dodecyl phenol condensed with about 18 moles of ethylene oxide(ethoxylated dodecyl phenol +75.3% EtO). The former was found to haveaviscosity in centistokes of 3.90 at 100 F., while the latter was foundto have a viscosity in centistokes of 3.70 at 100 F.

Example III TABLE 2 Ethylene Glycol-Water 50-50, parts by weight Cone.10% Ethoxylated Thickener KV-IOO Cloud Pt. F.)

2. 14 Dodeeyl phenol plus 75.3% EtO 4. 32 210 Nonyl phenol plus 67.8%EtO 4. 3 210 Dinonyl phenol plus 65.8% EtO. 12.65 190 Example IV Threeseparate hydraulic fluid compositions were prepared. The firstcomposition was made up of 9.0 parts by weight of a mixture of ethyleneglycol and water, and parts by weight of ethoxylated dinonyl phenol+65.8% EtO. The second composition was made up of 86 parts by weight ofa mixture of ethylene glycol and water, and 14 parts by weight ofethoxylated dinonyl phenol +65.8% EtO and the third composition was madeup of 82 parts by weight of a mixture of ethylene glycol and water; and18 parts by weight of ethoxylated dinonyl phenol +65% EtO. The ethyleneglycol-water mixture in all three compositions was made up of 65 percentethylene glycol and 35 percent water. The viscosities in centistokes ofthe three compositions at 100 F. were determined and the results were asfollows:

TABLE 3 Ethylene Glycol-Water 65-35, Cone. Ethoxylated Dinonyl Phenolparts by weight Plus 65.8% EtO KV-IOO Cloud Pt. F.)

Example V Three separate hydraulic fluid compositions were prepared. Thefirst composition was made up of 90 parts by weight of a mixture ofethylene glycol and water, and 10 parts by weight of ethoxylated dinonylphenol +70% EtO. The second composition was made up of 86 parts byWeight of a mixture of ethylene glycol and water, and 14 parts by weightof ethoxylated dinonyl phenol +70% E tO and the third composition wasmade up of 82 partsby weight of a mixture of ethylene glycol and water,and. 18 parts by weight of ethoxylated dinonyl phenol +70% EtO. Theethylene glycol-water mixture in all three compositions was made up ofpercent ethylene glycol and 35 percent water. The viscosities incentistokes of the three compositions at 100 F. were determined and theresults were as follows:

TAB LE 4 Ethylene Glycol-Water 65-35,

parts by weight Cone. Ethoxylated Dinonyl Phenol Plus EtO Variousmodifications and variations of this invention will be obvious to aworker skilled in the art and it is understood that such modificationsand variations are to be included within the purview of this applicationand the spirit and scope of the appended claims.

I claim:

1. A hydraulic fluid composition comprising (1) to 92 parts by weight ofan ethylene glycol-water mixture and (2) as a thickening agent, 25 to 8parts by weight 0t an ethoxylated dinonyl phenol in which itspolyoxethylene radical comprises 60 to 70% by weight of said ethoxylateddinonyl phenol; parts of said ethylene glycol-water mixture consistingessentially of about 40 to 65 parts by weight of ethylene glycol andabout 60-35 parts by weight of Water.

2. A hydraulic fluid composition according to claim 1, wherein theethylene glycol-water mixture consists essentially of about 50-65 partsby weight of ethylene glycol and about 50-35 parts by weight of water.

3. A hydraulic fluid composition according to claim 1, wherein thethickening agent is an ethoxylated dinonyl phenol in which itspolyoxyethylene radical comprises 65.8% by weight of said ethoxylateddinonyl phenol.

4. A hydraulic fluid composition according to claim 1, wherein thethickening agent is an ethoxylated dinonyl phenol in which itspolyoxethylene radical comprises 70% by weight of said ethoxylateddinonyl phenol.

5. A hydraulic fluid composition according to claim 3, wherein theethylene glycol-water mixture consists essentially of about 50 parts byweight of ethylene glycol and 50 parts by weight of water.

References Cited UNITED STATES PATENTS MURRAY KATZ, Primary Examiner.

S. D. SCHWARTZ, Assistant Examiner.

1. A HYDRAULIC FLUID COMPOSITION COMPRISING (1) 75 TO 92 PARTS BY WEIGHTOF AN ETHYLENE GLYCOL-WATER MIXTURE AND (2) AS A THICKENING AGENT, 25 TO8 PARTS BY WEIGHT OF AN ETHOXYLATED DINONYL PHENOL IN WHICH ITSPOLYOXETHYLENE RADICAL COMPRISES 60 TO 70% BY WEIGHT OF SAID ETHOXYLATEDDINONYL PHENOL; 100 PARTS OF SAID ETHYLENE GLYCOL-WATER MIXTURECONSISTING ESSENTIALLY OF ABOUT 40 TO 65 PARTS BY WEIGHT OF ETHYLENEGLYCOL AND ABOUT 60-35 PARTS BY WEIGHT OF WATER.